In centrifuging apparatus, constituents/components of a given material (e.g., liquid solutions/mixtures) can be separated based upon the variation of their respective densities and the centrifugal forces to which such constituents/components are subjected. Generally, the material is positioned within a centrifuge bowl which is rotated at a speed such that the various constituents will effectively assume a radial position within the bowl based upon their respective densities (i.e., constituents having higher densities will be closer to the rim of the centrifuge bowl than those having lower densities).
During rotation of the centrifuge bowl, which is often at relatively high angular velocities in order to generate the magnitude of centrifugal forces needed for separation, the temperature of the bowl and the materials contained therein may undesirably change. For instance, certain materials and/or constituents may experience undesired degradation at ambient temperature. Moreover, certain temperatures may have an undesirable/adverse effect on certain reactions/processes which take place during centrifuging, or may actually cause an undesirable reaction amongst certain of the constituents. In addition, certain temperatures may impede the separation of certain constituents from the remainder of the material by centrifuging.
Based upon the foregoing, a number of alternatives have been explored for establishing and/or maintaining a temperature of a centrifuge and thus the material within the centrifuge bowl. For instance, it is known to enclose the entire centrifuge within a temperature-controlled housing. More particularly, the air within the housing is maintained at the desired temperature so as to maintain the centrifuged material at such temperature by convection. In these types of configurations, given the heat transfer inefficiencies of convection utilizing air as the heat transfer medium, it is important to maintain an air-tight seal for the housing in order to maintain temperature control. Consequently, any opening of the housing to remove and/or add materials to the centrifuge will thus affect the housing temperature, and upon any subsequent closing of the housing a certain period of time will be required before the desired steady-state temperature is once again reached.
In contrast to attempting to maintain the temperature of the entire centrifuge by utilizing the above-described types of temperature-controlled housings, other apparatus have attempted to directly cool or heat only the periphery of the centrifuge bowl. For instance, U.S. Pat. No. 3,981,437 to Hemfort et al., issued Sep. 21, 1976, discloses positioning an insert having a plurality of circumferentially spaced ribs against the outer wall or drum of the centrifuge. The ribs form a plurality of passageways between the insert and the drum such that coolant may be injected in and flow through the passageways. The coolant flows through the passageways and is discharged through a plurality of radial ports in the drum for engagement with a stationary casing which is spaced from the rotating drum and which incorporates a cooling jacket to reduce the temperature of the coolant prior to its recirculation to the periphery of the drum.
Temperature control systems have also been incorporated on other types of rotating apparatus. For instance, certain analyzers are available in which a plurality of cuvettes are positioned on an outer portion of a rotor. These cuvettes typically have a relatively small volume for receiving at least two different constituents which are initially maintained in separate but interconnected cavities in the rotor. As a result of the centrifugal forces created by rotation of the rotor at a certain speed, the constituents from the separate cavities enter a radially aligned cuvette. The reaction of the two constituents in each cuvette is then monitored and/or analyzed. Since the reaction of the constituents is often temperature-sensitive, heating devices are often employed so as to maintain the peripherally-positioned cuvettes and their constituents at a certain temperature.
Various temperature control alternatives have been explored for cuvette rotors which are generally of the above-described type. For instance, hot air has been used to control either the temperature of an entire housing in which the cuvette rotor is positioned, or at least the space between the periphery of the rotor, which again contains the cuvettes, and the rotor housing. U.S. Pat. Nos. 3,916,152 to Hinman, issued Oct. 28, 1975, and 4,135,883 to McNeil et al., issued Jan. 23, 1979, are generally representative of these efforts. Other apparatus have incorporated heating elements directly on the periphery of the rotor substantially adjacent to the cuvettes to provide for a conductive heat transfer as representatively disclosed in U.S. Pat. Nos. 3,856,470 to Cullis et al., issued Dec. 24, 1974 and 4,256,696 to Soodak, issued Mar. 17, 1981.
Notwithstanding the foregoing, there remains a need for a temperature control system which may be readily adapted for use with centrifuges of a variety of configurations, and which effectively regulates the temperature of substantially the entire centrifuge bowl and materials contained therein without significantly impacting the structure of an existing centrifuge and/or without requiring extensive modifications/additions to the centrifuge and its surroundings.